Reuse Prism parse result for RuboCop (#3584)

Author: vinistock

lib/ruby_lsp/requests/support/rubocop_formatter.rb

@@ -24,7 +24,7 @@ def run_formatting(uri, document)
           filename = uri.to_standardized_path || uri.opaque #: as !nil
 
           # Invoke RuboCop with just this file in `paths`
-          @format_runner.run(filename, document.source)
+          @format_runner.run(filename, document.source, document.parse_result)
           @format_runner.formatted_source
         end
 
@@ -40,7 +40,7 @@ def run_range_formatting(uri, source, base_indentation)
         def run_diagnostic(uri, document)
           filename = uri.to_standardized_path || uri.opaque #: as !nil
           # Invoke RuboCop with just this file in `paths`
-          @diagnostic_runner.run(filename, document.source)
+          @diagnostic_runner.run(filename, document.source, document.parse_result)
 
           @diagnostic_runner.offenses.map do |offense|
             Support::RuboCopDiagnostic.new(

lib/ruby_lsp/requests/support/rubocop_runner.rb

@@ -81,6 +81,7 @@ def initialize(*args)
           @offenses = [] #: Array[::RuboCop::Cop::Offense]
           @errors = [] #: Array[String]
           @warnings = [] #: Array[String]
+          @prism_result = nil #: Prism::ParseLexResult?
 
           args += DEFAULT_ARGS
           rubocop_options = ::RuboCop::Options.new.parse(args).first
@@ -92,14 +93,15 @@ def initialize(*args)
           super(rubocop_options, config_store)
         end
 
-        #: (String path, String contents) -> void
-        def run(path, contents)
+        #: (String, String, Prism::ParseLexResult) -> void
+        def run(path, contents, prism_result)
           # Clear Runner state between runs since we get a single instance of this class
           # on every use site.
           @errors = []
           @warnings = []
           @offenses = []
           @options[:stdin] = contents
+          @prism_result = prism_result
 
           super([path])